Heart Disorders in Pregnancy
Heart disorders account for about 10% of maternal obstetric deaths. In the US, because incidence of rheumatic heart disease has markedly declined, most heart problems during pregnancy result from congenital heart disease. However, in Southeast Asia, Africa, India, the Middle East, and parts of Australia and New Zealand, rheumatic heart disease is still common.
Despite dramatic improvements in survival and quality of life for patients with severe congenital heart defects and other heart disorders, pregnancy remains inadvisable for women with certain high-risk disorders such as the following (1):
Pulmonary hypertension (pulmonary artery systolic pressure > 25 mm Hg) caused by any condition, including Eisenmenger syndrome
Coarctation of the aorta if uncorrected or if accompanied by an aneurysm
Marfan syndrome with aortic root diameter of > 4.5 cm
Bicuspid aortic valve with ascending aorta diameter > 50 mm
A single ventricle and impaired systolic function (whether treated with the Fontan procedure or not)
Cardiomyopathy with ejection fraction < 30% or New York Heart Association (NYHA) class III or IV heart failure (see table New York Heart Association (NYHA) Classification of Heart Failure)
1. European Society of Gynecology (ESG); Association for European Paediatric Cardiology (AEPC); German Society for Gender Medicine (DGesGM): ESC Guidelines on the management of cardiovascular diseases during pregnancy: the Task Force on the Management of Cardiovascular Diseases During Pregnancy of the European Society of Cardiology (ESC). Eur Heart J 32 (24):3147–3197, 2011. doi: 10.1093/eurheartj/ehr218.
Pregnancy stresses the cardiovascular system, often worsening known heart disorders; mild heart disorders may first become evident during pregnancy.
Stresses include decreased hemoglobin and increased blood volume, stroke volume, and eventually heart rate. Cardiac output increases by 30 to 50%. These changes become maximal between 28 and 34 weeks gestation.
During labor, cardiac output increases about 20% with each uterine contraction; other stresses include straining during the 2nd stage of labor and the increase in venous blood returning to the heart from the contracting uterus. Cardiovascular stresses do not return to prepregnancy levels until several weeks after delivery.
Findings resembling heart failure (eg, mild dyspnea, systolic murmurs, jugular venous distention, tachycardia, dependent edema, mild cardiomegaly seen on chest x-ray) typically occur during normal pregnancy or may result from a heart disorder. Diastolic or presystolic murmurs are more specific for heart disorders.
Heart failure can cause premature labor or arrhythmias. Risk of maternal or fetal death correlates with NYHA functional classification, which is based on the amount of physical activity that causes symptoms of heart failure.
Risk is increased only if symptoms
Diagnosis of a heart disorder during pregnancy is usually based on clinical evaluation and echocardiography.
Because genetics can contribute to the risk of heart disorders, genetic counseling and fetal echocardiography should be offered to women with congenital heart disease.
Avoidance of warfarin, angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), aldosterone antagonists, thiazide diuretics, and certain antiarrhythmics (eg, amiodarone)
For NYHA class III or IV, activity restriction and possibly bed rest after 20 weeks
Most other usual treatments for heart failure and arrhythmias
Frequent prenatal visits, ample rest, avoidance of excessive weight gain and stress, and treatment of anemia are required. An anesthesiologist familiar with heart disorders in pregnancy should attend the labor and ideally should be consulted prenatally. During labor, pain and anxiety are treated aggressively to minimize tachycardia. Women are closely monitored immediately postpartum and are followed for several weeks postpartum by a cardiologist.
Before women with NYHA class III or IV status conceive, the disorder should be optimally treated medically and, if indicated (eg, if due to a valvular heart disorder), treated surgically. Women with class III or IV heart failure or another high-risk disorder (listed above) may be advised to obtain an early therapeutic abortion.
Some women with a heart disorder and poor cardiac function require digoxin 0.25 mg po once a day plus bed rest or limited activity, beginning at 20 weeks. Cardiac glycosides (eg, digoxin, digitoxin) cross the placenta, but neonates (and children) are relatively resistant to their toxicity. ACE inhibitors and ARBs are contraindicated because they may cause fetal renal damage. Aldosterone antagonists (spironolactone, eplerenone) should be avoided because they may cause feminization of a male fetus. Other treatments for heart failure (eg, nonthiazide diuretics, nitrates, inotropes) may be continued during pregnancy depending on disease severity and fetal risk, as determined by a cardiologist and a perinatologist.
Atrial fibrillation may accompany cardiomyopathy or valvular lesions. Rate control is usually similar to that in nonpregnant patients, with beta-blockers, calcium channel blockers, or digoxin (see Drugs for Arrhythmias). Certain antiarrhythmics (eg, amiodarone) should be avoided. If pregnant patients have new-onset atrial fibrillation or hemodynamic instability or if drugs do not control ventricular rate, cardioversion may be used to restore sinus rhythm.
Anticoagulation may be required because the relative hypercoagulability during pregnancy makes atrial thrombi (and subsequent systemic or pulmonary embolization) more likely. Standard or low molecular weight heparin is used. Neither standard heparin nor low molecular weight heparins cross the placenta, but low molecular weight heparins may have less risk of thrombocytopenia. Warfarin crosses the placenta and may cause fetal abnormalities (see table Some Drugs With Adverse Effect During Pregnancy), particularly during the 1st trimester. However, risk is dose-dependent, and incidence is very low if the dose is ≤ 5 mg per day. Warfarin use during the last month of pregnancy has risks. Rapid reversal of warfarin’s anticoagulant effects may be difficult and may be required because of fetal or neonatal intracranial hemorrhage resulting from birth trauma or because of maternal bleeding (eg, resulting from trauma or emergency cesarean delivery).
For pregnant patients with a structural heart disorder, indications and use of endocarditis prophylaxis for nonobstetric events are the same as those for nonpregnant patients. The American Heart Association guidelines do not recommend endocarditis prophylaxis for vaginal and cesarean deliveries because the rate of bacteremia is low. However, in the highest-risk patients (eg, those with prosthetic heart materials, a history of endocarditis, an unrepaired congenital cyanotic heart lesion, or a heart transplant with a valvulopathy), prophylaxis is often considered when the membranes rupture, even though no evidence indicates any benefit.
If patients with a structural heart disorder develop chorioamnionitis or another infection (eg, pyelonephritis) requiring hospital admission, the antibiotics used to treat the infection should cover the pathogens most likely to cause endocarditis.
Pregnancy may not be advisable for women with certain high-risk heart disorders (eg, pulmonary hypertension, coarctation of the aorta if uncorrected or accompanied by an aneurysm, Marfan syndrome with aortic root diameter of > 4.5 cm, severe symptomatic aortic stenosis, severe mitral stenosis, bicuspid aortic valve with ascending aorta > 50 mm, a single ventricle with impaired systolic function, cardiomyopathy, NYHA class III or IV heart failure).
Treat heart failure and arrhythmias during pregnancy as for nonpregnant patients, except avoid certain drugs (eg, warfarin, ACE inhibitors, ARBs, aldosterone antagonists, thiazide diuretics, certain antiarrhythmics such as amiodarone).
Treat most pregnant patients who have atrial fibrillation with standard or low molecular weight heparin.
Indications for endocarditis prophylaxis for pregnant patients with a structural heart disorder are the same as those for other patients.
During pregnancy, stenosis and regurgitation (insufficiency) most often affect the mitral and aortic valves. Mitral stenosis is the most common valvular disorder during pregnancy.
Pregnancy amplifies the murmurs of mitral stenosis and aortic stenosis but diminishes those of mitral and aortic regurgitation. During pregnancy, mild mitral or aortic regurgitation is usually easy to tolerate; stenosis is more difficult to tolerate and predisposes to maternal and fetal complications. Mitral stenosis is especially dangerous; the tachycardia, increased blood volume, and increased cardiac output during pregnancy interact with this disorder to rapidly increase pulmonary capillary pressure, causing pulmonary edema. Atrial fibrillation is also common.
Ideally, valvular disorders are diagnosed and treated medically before conception; surgical correction is often recommended for severe disorders. Prophylactic antibiotics are required in certain situations (eg, for endocarditis prophylaxis).
Patients must be closely observed throughout pregnancy because mitral stenosis may rapidly become more severe. If required, valvotomy is relatively safe during pregnancy; however, open heart surgery increases fetal risk. Tachycardia should be prevented so that diastolic flow through the stenotic mitral valve can be maximized.
If pulmonary edema occurs, loop diuretics can be used.
If atrial fibrillation occurs, anticoagulation and control of heart rate are necessary. Control of heart rate is usually similar to that in nonpregnant patients and involves beta-blockers, calcium channel blockers, or digoxin (see Drugs for Arrhythmias).
During labor, conduction anesthesia (eg, slow epidural infusion) is usually preferred.
Aortic stenosis should be corrected before pregnancy if possible because surgical repair during pregnancy has more risks and catheter valvuloplasty is not very effective.
During labor, local anesthesia is preferred, but if necessary, general anesthesia is used. Conduction anesthesia should be avoided because it decreases filling pressures (preload), which may already be decreased by aortic stenosis.
Straining, which can suddenly reduce filling pressures and impair cardiac output, is discouraged during the 2nd stage of labor; operative vaginal delivery is preferred. Cesarean delivery is done if indicated for obstetric reasons.
Mitral valve prolapse occurs more frequently in younger women and tends to be familial. Mitral valve prolapse is usually an isolated abnormality that has no clinical consequences; however, patients may also have some degree of mitral regurgitation. Rarely, mitral valve prolapse occurs with Marfan syndrome or an atrial septal defect.
Women with mitral valve prolapse and resulting mitral regurgitation generally tolerate pregnancy well. The relative increase in ventricular size during normal pregnancy reduces the discrepancy between the disproportionately large mitral valve and the ventricle.
Beta-blockers are indicated for recurrent arrhythmias. Rarely, thrombi and systemic emboli (due to concomitant atrial fibrillation) develop and require anticoagulation.
For most asymptomatic patients, risk is not increased during pregnancy. However, patients with Eisenmenger syndrome (now rare), primary pulmonary hypertension, or perhaps isolated pulmonary stenosis are predisposed, for unknown reasons, to sudden death during labor, during the postpartum period (the 6 weeks after delivery), or after abortion at > 20 weeks gestation. Thus, pregnancy is inadvisable. If these patients become pregnant, they should be closely monitored with a pulmonary artery catheter and/or an arterial line during delivery.
For patients with intracardiac shunts, the goal is to prevent right-to-left shunting by maintaining peripheral vascular resistance and by minimizing pulmonary vascular resistance.
Patients with Marfan syndrome are at increased risk of aortic dissection and rupture of aortic aneurysms during pregnancy. Bed rest, beta-blockers, avoidance of Valsalva maneuvers, and measurement of aortic diameter with echocardiography are required.
Heart failure with no identifiable cause (eg, myocardial infarction, valvular disorder) can develop between the last month of pregnancy and 6 months postpartum in patients without a previous heart disorder (1). Risk factors include
The 5-year mortality rate is 50%. Recurrence is likely in subsequent pregnancies, particularly in patients with residual cardiac dysfunction; future pregnancies are therefore not recommended.
Treatment is as for heart failure. ACE inhibitors and aldosterone are relatively contraindicated but may be used when the expected benefit clearly exceeds the potential risks.
1. Sliwa K, Hilfiker-Kleiner D, Petrie MC, et al: Current state of knowledge on aetiology, diagnosis, management, and therapy of peripartum cardiomyopathy: A position statement from the Heart Failure Association of the European Society of Cardiology Working Group on peripartum cardiomyopathy. Eur J Heart Fail 12 (8):767–778, 2010. doi: 10.1093/eurjhf/hfq120.
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